Mrs. James in Barbados prepares guava jam using the open kettle method. Which preservation principle is primarily responsible for preventing microbial growth in the finished jam?

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Question

Mrs. James in Barbados prepares guava jam using the open kettle method. Which preservation principle is primarily responsible for preventing microbial growth in the finished jam?

Accepted Answer

High sugar concentration creating hypertonic conditions — Award 1 mark for identifying that the high sugar content (65-70%) in jam creates a hypertonic environment that draws water out of microbial cells through osmosis, preventing their growth. A is incorrect — while acid is added, the primary preservation method is sugar concentration. C is incorrect — oxygen exclusion is secondary to sugar's preservative effect. D is incorrect — high pressure processing is not used in traditional jam-making.

Answer

Application of high pressure

Answer

Exclusion of oxygen from the jar

Answer

High sugar concentration creating hypertonic conditions

Answer

Addition of acid to lower pH

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